An unregistered trademark generally enjoys no legal protection, meaning any third party can copy it and sell his goods or services under it. Once a trademark is registered, only the rightsholder is allowed to use the mark. Holders of a registered trademark have a very strong legal standing in court procedures against other parties who copied their trademarks. On top of that, once you filed an application for trademark registration, anyone filing an application for registration of the same trademark after you will not be granted registration.